1. Field of Invention
The present invention relates to a apparatus for inspecting an illumination optical device. In particular, the invention relates to an apparatus for inspecting the optical characteristics of an illumination optical device constituting an illumination optical system that condenses a luminous flux emitted from a light source lamp to form an optical image. The invention also relates to a method for inspecting a lens array serving as the illumination optical device.
2. Description of Related Art
Projectors can be used for presentations or the like. Projectors can be equipped with a light source lamp, an electro-optical device that modulates a luminous flux emitted from the light source lamp according to image information, and a projection optical system to enlarge and projecting the luminous flux modulated by the electro-optical device.
In such a projector, an illumination optical system is frequently disposed between the light source lamp and the electro-optical device to evenly illuminate an image forming region of the electro-optical device by the luminous flux emitted from the light source lamp.
A related art illumination optical system uses a lens array acting as a luminous flux splitting device constituted by a plurality of planar semicircular (plano-convex lenses) small lenses arranged in a matrix pattern in the plane orthogonal to the direction in which light is emitted.
In such a construction, the illumination optical system splits the luminous flux emitted from the light source lamp into a plurality of partial luminous fluxes by a plurality of small lenses making up the lens array, to superimpose the partial luminous fluxes in the image forming region of the electro-optical device so as to evenly illuminate the image forming region. This makes it possible to obtain a sharp projection image free of uneven luminance.
The lens array is fabricated as follows. First, a molten glass or resin material is poured into a mold having the configuration for the plurality of small lenses making up the lens array so as to mold the small lenses, or softened glass is press-molded using a mold to obtain the small lenses. Then, these plural small lenses are disposed at predetermined positions and subjected to heat treatment so as to fabricate a lens array formed of the integrated small lenses.